This invention relates generally to signal processing and more specifically to a method and apparatus for increasing the precision and dynamic range of processed signals.
There is a demand in many electronics applications for increased precision and dynamic range. This demand for increased precision is especially acute in imaging sensors, particularly in the areas of automotive sensing systems associated smart driving, and certain surveillance applications. Current imaging sensors for CMOS active pixel sensors, are limited to about 12 bits for on chip analog-to-digital converters. Attempts have been made to incorporate analog-to-digital converters within the pixel or quad pixels to exploit the improved local signal-to-noise ratio. These attempts have generally not succeeded in achieving the desired improvement of precision, dynamic range, and signal-to-noise ratio at a chip level. Therefore it would be desirable to provide an improvement of precision, dynamic range, and signal-to-noise ratio.
The present invention relates generally to improving the performance of analog-to-digital converters. The invention provides a method and apparatus for improving the resolution of analog-to-digital converters by providing a signal from a source and locally processing a first portion of the signal to produce a processed signal. The remaining portion of the signal is non-locally converted to produce a first digital signal. The processed signal is converted non-locally to produce a second digital signal, finally the first digital signal is combined, using either a common analog-to-digital converter or a shared analog-to-digital converter, with the second digital signal to produce a digital output signal.
Another embodiment includes providing a signal from a source and locally converting a first portion of the signal to produce a first digital signal. The remaining portion of the signal is non-locally converted to produce a second digital signal. The first digital signal is combined with the second digital signal to produce a digital output signal using either a common analog-to-digital converter or a shared analog-to-digital converter.
In another embodiment a signal is provided from a source, and a portion of that is processed to produce a processed signal. The remaining portion of the signal is non-locally converted to produce a first digital signal. The processed signal is converted to produce a second digital signal, finally the first digital signal is combined with the second digital signal to produce a digital output signal using either a common analog-to-digital converter or a shared analog-to-digital converter.
In the above embodiments the local processing of the first portion of the signal can be done with a quantizing processor utilizing a waveform generating element that generates a waveform utilizing either an analog circuit configured to generate a waveform or a digital logic circuit and a digital to analog converter configured to generate an analog waveform. In the second embodiment listed above the conversion of the first portion of the signal can be generated with a local analog-to-digital converter. Additionally the signal can be generated at a source such as an electromagnetic radiation sensor where the sensor could be a pixel.